*ith the 
tions, 
: 
2 
ign 
: 
2 
: 
P= 
re: 
a 
a 
. 
1894] 
Leaf Movement in Cercis. 221 
vinus. The bast which occupies the outer portion of the 
fibrovascular region forms a complete ring of closely set thick 
walled cells, and together with the woody tissues evidently 
constitutes the fulcrum or negative element in producing the 
tal movement. By the use of the phloroglucin? test for 
lignin it was found that in the petiole the wood-cells, scala- 
tiform vessels and bast were highly lignified, while in the 
pulvinus only the scalariform vessels with some traces in the 
wood-cells gave the lignin reaction. The bast in the pulvi- 
ius was entirely unlignified and seemed to be much more 
tasily macerated by the acid used in the test than in other 
parts. In the pulvinus the bast is much more closely packed 
sound the woody tissue, the sieve-tubes and phloem paren- 
chyma being less prominent than in the petiole. The posi- 
tion of these various tissues will be seen by an examination 
of figs. 4-12 inclusive, plate xx, which are intended, how- 
“ver, to show chiefly the changes in position of the fibrovas- 
cular bundles as they pass through the pulvinus. Fig. 4 is 
from a transverse section made at about the middle point of 
the petiole. The fibrovascular * portions occupy a single 
completed ting surrounding a centrally placed mass of 
pareachy ma. In fig. 5, which is from a transverse section 
Coely below the upper pulvinus, the fibrovascular part 
i. vided into two complete rings, in the larger of which there 
SO Pane of still farther subdivision. Figs. 6-11 inclusive 
Pa transverse sections through the upper pulvinus 
t €qually distant from each other from the base to the 
there | hg. 6, which is from the lowest section in the anes 
._,» Still more evidence of subdivision than in fig. 5 the 
tinet s 5 ent of parts culminating in fig. 10 in three dis- 
ith tho wes arranged as nearly as possible in a single plane, 
ast tissues closely packed around the woody por- 
i ony the paint of See 
* See explany biological Botany, 14. 
‘on of plates, for lettering of drawings. 
